German Patent No. 100 17 280, for example, describes a method and a device for controlling an internal combustion engine. The patent describes a method and a device for controlling an internal combustion engine in which the oxygen quantity flowing into the internal combustion is determined with the aid of at least one model on the basis of at least one manipulated variable and at least one measured variable characterizing the condition of the air in an intake manifold. Furthermore, a signal regarding the oxygen concentration in the exhaust-gas tract is ascertained, which corresponds to the output signal of a lambda probe.